1. Field of the Invention
The invention relates to a display apparatus having display means comprising, for example, a liquid crystal panel or the like.
2. Related Background Art
Hitherto, a display apparatus having a display unit comprising, for example, a liquid crystal panel or the like is constructed as shown in, for instance, FIG. 37. In the diagram, a display apparatus 500 is mainly made up of a display unit 501 comprising a liquid crystal panel or the like, a keyboard 502 to input information, and a main body 503 of the display apparatus.
In such a display apparatus, when inputting by the keyboard 502, the display unit 501 is provided for the operator to only look at the display contents. The display unit 501 is constructed so that it can be moved in directions A in the diagram.
As shown in FIG. 38, when inputting by an input pen 504, the display apparatus 500 fixes the display unit 501 to a position where the operator can easily input by using the input pen 504.
As shown in FIGS. 39, 40, and 41, the display apparatus 500 is constructed in a manner such that the position of the display unit 501 is changed by using connecting portions 506 and 507 as fulcrums, thereby changing from a form shown in FIG. 37 to a form shown in FIG. 38.
As such a kind of apparatus, the apparatus supported by a stand having a mechanism such that a tilting angle of a display screen can be varied in accordance with a body size or a posture of the user or an environment (light reflection of the external light or the like) of a use location is used. There is also an apparatus constructed so that a swiveling operation can be performed.
Particularly, in recent years, the realization of a large screen of a liquid crystal display device is progressing and a thin size of the apparatus has been realized. Therefore, in an apparatus such that the tilting operation is performed by setting a state in which the screen is almost vertical to the desk surface to a reference state in a manner similar to the CRT, in order to miniaturize an installation area, the depth dimension of a stand for supporting the screen is reduced. On the other hand, in an apparatus such that an inputting operation is performed by directly operating on the screen like a touch panel or a pen input apparatus, an apparatus in which an angle of screen lies within a range from a state where it is parallel with the desk surface to about 30.degree. such that the operator can easily operate even in case of the desk-top type has been realized and is started to be put into practical use. In case of the CRT, although it is necessary to bury the CRT into the desk, such an angle could be realized owing to the thin size of the apparatus. As mentioned above, in case of the apparatus in which an angle of screen is set to a small angle, since a viewpoint of the user can be set to be downward, it is also desirable from a point of prevention of a visual disease such as a dry eyes or the like.
An apparatus using a rotary arm in such a display apparatus has been described in U.S. Pat. No. 4,438,458 issued Mar. 20, 1984 to Munscher. By using the rotary arm, an angle of screen can be varied from the horizontal state to an almost vertical state and a height can be also changed.
In a display apparatus having a display device made of liquid crystal or the like as mentioned above, particularly, in a display apparatus having a display device with a temperature dependency with respect to a display speed of liquid crystal or a luminance of a back light, it is necessary to suppress an increase in temperature in a casing enclosing the display apparatus as much as possible. For this purpose, a method of forcedly cooling by attaching a fan or a method of radiating by a natural convection is used.
However, the above conventional display apparatus has a problem such that it can be fixed to only two points of a position (FIG. 37) where it is used only for seeing the display contents and a position (FIG. 38) at the time of inputting by using the pen or the like, so that the display apparatus cannot be fixed to an arbitrary position between those two points.
However, the conventional apparatus has some inconveniences. That is, when the display screen is large in size, since a weight also increases, a large force is necessary to adjust the screen angle and there is a drawback such that it is difficult to use the apparatus. Even in a state in which the screen is made to stand vertically, an installation space on the desk corresponding to almost a length in vertical direction of the display unit is necessary. In order to vertically put the apparatus in a folded state, it is necessary to once lift up the main body and it is inconvenient in case of the apparatus with a large size. When the angle of screen is changed, since the center of gravity moves forward and backward, a stability is also insufficient. Moreover, if the weight is especially large and a moving force is large, there is a fear such that a finger or the like of the user is sandwiched between the rotary arm and a base seat portion or a display unit and the user is seriously externally wound. There is, consequently, a problem on safety. Further, in case of an apparatus for directly inputting onto the screen by using a pen or a finger, since a pressing force is applied onto the screen surface, it is necessary to fix the screen in a state in which the tilting angle is variably set so as not to move the screen during the operation. However, there is not any apparatus having such a function.
In case of inclining and using the casing, since a flow of air in the casing changes depending on the angle of inclination, there is a fear such that an internal temperature changes and a desired temperature control cannot be performed. In such a case, a method of providing a fan with a temperature sensor is also considered. However, such a fan results in an increase in costs. Since a parameter for an on/off control of the fan is only a temperature, the fan continuously rotates in accordance with the temperature. In dependence on a use form, there is also a case where even if a display speed, a luminance, or the like of liquid crystal is sacrificed, it is difficult to stop the fan and to realize an electric power saving or silence. Further, a case where an obstacle is produced in front of an air exhaust port depending on an angle of the casing is also considered. That is, the temperature control cannot be properly performed depending on the position of the casing enclosing the display apparatus, so that there is a problem such that the temperature change cannot be suppressed.